The present invention relates to a method of controlling a mechanical auxiliary unit in a motor vehicle by means of a device consisting of a control unit and a switch for switching the unit on and off. The invention also relates to a device for implementing the said method.
Examples of mechanical auxiliary units of this nature include auxiliary heaters and air conditioning units. Units of this xe2x80x98seasonalxe2x80x99 type are used intensively during winter or summer periods and, thereafter, remain basically unused until the next period of use. The use of components which require maintenance to ensure their life is also a common feature of such units. In many cases, it is sufficient to operate the unit for a short period at regular intervals to condition these components, examples of which include seals and gaskets which must be exposed to fluids to prevent drying and ageing, non-friction bearings in which the metallic and line contacts must be shifted when the bearings are subjected to vibrations of long duration, such as in an internal combustion engine, and liquids which may thicken and cause blockages in lines, which may also dry out when the liquid level falls.
One purpose of the invention is to provide a method and a device of the type already described which, by simple means, can ensure the maintenance operation of auxiliary units, thereby preventing operating faults and prolonging the life of the unit.
In one aspect of the invention, the control unit includes a program designed to repeatedly signal the following steps:
switch-on of the unit when it is in the switched-off state at a particular point in time and has not been switched on for a long period of at least some weeks, and
switch-off of the unit switched on as described, after a short period of at least some minutes.
In one embodiment of the invention, the control unit program may be designed to deliver a switch-on signal only if the aforementioned specific point in time falls within a seasonal interval of at least some months.
Other characteristics and advantages of the invention are manifest from the embodiment description and from the patent claims.
Although it has long been known practice to equip an auxiliary heater, for example, with a timer function, it has not hitherto been realised that such a unit can be complemented easily with characteristics in accordance with the present invention.